This present invention relates to three-dimensional (3-D) modeling in general and to a system and a method for 3-D printing of complex structures in particular.
3-D printing, which works by building parts in layers, is a process used for the building up of 3-D models. 3-D printing is relatively speedy and flexible allowing for the production of prototype parts and tooling directly from a CAD model, for example.
Using 3-D printing enables the manufacturer to obtain a full 3-D model of any proposed product before tooling thereby possibly substantially reducing the cost of tooling and loading to a better synchronization between design and manufacturing. A lower product cost and improved product quality can also be obtained.
Various systems have been developed for computerized 3-D printing. Known systems include a system developed by 3-D Systems Inc. of California, USA, which operates on the basis of stereo-lithography wherein a focused ultra-violet laser is scanned over the top of a bath of photopolymerizable liquid polymer plastic material. The surface of the bath is polymerized on contact with the UV laser creating a solid plastic layer at or just below the surface
U.S. Pat. No. 5,387,380 to Cima et al. describes a technique for providing layered parts by depositing a layer of powder material and then depositing a binder material in selected regions to produce a layer of bonded powder material at the selected regions. These steps are repeated for successive layers to form a desired component. Following heat treatment, unbound powder is removed, leaving the fabricated part.
U.S. Pat. No. 5,287,435 to Cohen et al describes apparatus for producing 3-D models which includes apparatus for depositing layer-by-layer, a photopolymer material in a selectable configuration and apparatus for curing each layer prior to deposition of the succeeding layer.
A disadvantage of these systems is the difficulty of printing 3-D models having a complex structure such as a tea cup, for example (shown in FIG. 2).
In U.S. patent application Ser. No. 09/259,323 to the Assignees of the present application, and incorporated herein by reference, there is described an apparatus and a method for 3-D model printing. U.S. patent application Ser. No. 09/259,323 describes apparatus including a printing head having a plurality of nozzles, a dispenser connected to the printing head for selectively dispensing interface material in layers and curing means for optionally curing each of the layers deposited. The depth of each deposited layer is controllable by selectively adjusting the output from each of the plurality of nozzles.
The present invention provides a 3-D printing system and a method for printing complex 3-D models by utilizing at least two printing heads which eject interface material. By using interface material having different hardness (or modulus of elasticity) and mixing the interface material from each of the printing heads, the hardness of the layers of material forming the 3-D model can be controlled. The layers forming the construction layers of the model are formed from interface material having a different (harder) modulus of elasticity from the layers forming the release layers, thereby allowing for the forming complex shapes.
There is thus provided, in accordance with a preferred embodiment of the present invention, a method for three-dimensional printing of a three-dimensional model. The method includes:
dispensing a first interface material from a printing head;
dispensing at least a second interface material from the printing head; and
combining the first and second interface material in pre determined proportions to produce construction layers for forming the three-dimensional model.
Furthermore, in accordance with a preferred embodiment of the present invention, the printing head includes first and second printing heads. The first interface material and second interface material are dispensed from the first and second printing heads, respectively.
Furthermore, in accordance with a preferred embodiment of the present invention, the method further includes the step of curing the first interface material for a first period of time and at a first radiation wavelength to obtain a first modulus of elasticity. The method further includes the step of curing the second interface material for a second period of time and at a second radiation wavelength to obtain a second modulus of elasticity.
Furthermore, in accordance with a preferred embodiment of the present invention, the step of combining includes the step of adjusting the relative proportions of the first and second interface materials, the first and second interface materials having different modulus of elasticity.
Furthermore, in accordance with a preferred embodiment of the present invention, the further includes the step of combining the first and second interface material in pre-determined proportions to form a release layer, the release layer having a lower modulus of elasticity than the construction layer. The release layer includes a plurality of release blocks, each of the release blocks having a pre-determined modulus of elasticity.
Furthermore, in accordance with a preferred embodiment of the present invention, 95 to 100% of the construction layer includes the first interface material and 0 to 5% of the construction layer includes the second interface material. 0 to 5% of the release layer includes the first interface material and 95 to 100% of the release layer includes the second interface material.
Additionally, in accordance with a preferred embodiment of the present invention, the first interface material is a different color than the second interface material. Furthermore, the first and/or second interface material is transparent.
There is additionally provided, in accordance with a preferred embodiment of the present invention, a system for three-dimensional printing of a three-dimensional model, which includes at least one printing head, having a plurality of nozzles, at least first and second dispensers connected to the printing head for dispensing at least first and second interface materials therefrom respectively, and control means connected to the printing head for combining at the first and second interface materials in pre-determined proportions to produce forming the three-dimensional model.
Furthermore, in accordance with a preferred embodiment of the present invention, the system further includes curing means for optionally curing the layers. The curing means includes a first curing means for curing the first interface material for a first period of time and at a first radiation wavelength to obtain a first modulus of elasticity; and a second curing means for curing the second interface material for a second period of time and at a second radiation wavelength to obtain a second modulus of elasticity.
The printing head includes first and second printing heads wherein the first interface material and second interface material are dispensed from the first and second printing heads, respectively.
Furthermore, in accordance with a preferred embodiment of the present invention, the layers comprise first construction layers and second release layers. The first construction layers and the second release layers have differing proportions of the first and the second interface materials, respectively, and different moduluses of elasticity.
Furthermore, in accordance with a preferred embodiment of the present invention, the system further includes positioning apparatus coupled to the control means for selectively positioning the first and second printing heads by commands from the control means.
In addition, there is provided, in accordance with a preferred embodiment of the present invention, a system for three-dimensional four-color printing of a three-dimensional model, which includes at least one printing head, having a plurality of nozzles, a plurality of dispensers connected to the at least one printing head for dispensing a plurality of interface materials and control means connected to the at least one printing head for combining the plurality of interface materials in pre-determined proportions to produce layers having different colors for forming the three-dimensional model.
Furthermore, in accordance with a preferred embodiment of the present invention, the printing head includes a plurality of printing heads and wherein each of the plurality of interface materials are dispensed from a different one of each of the plurality of printing heads, respectively.
Furthermore, in accordance with a preferred embodiment of the present invention, the system further includes curing means for optionally curing the layers. The curing means includes at least first curing means for curing at least one of the plurality of interface materials for a first period of time and at a first radiation wavelength to obtain a first modulus of elasticity. The system further includes a dispenser for dispensing transparent material.
Furthermore, in accordance with a preferred embodiment of the present invention, the layers have different moduluses of elasticity. The layers are a photopolymer material curable by the application of any one of a group including ultra violet radiation, infra red radiation and E-beam.